1. Field of the Invention
The present invention particularly relates to an inertial force sensor used in various electronic equipment, for example, used for altitude control, navigation, or the like, of a mobile body such as an aircraft, an automobile, a robot, a watercraft and a vehicle.
2. Background Art
In a conventional inertial force sensor, a tuning fork-shaped sense element is allowed to oscillate and an inertial force applied to the sense element is detected by using a Coriolis force. Therefore, in order to make the amplitude of the sense element constant, an AGC circuit is provided in a drive circuit for oscillating the sense element. Prior art information relating to the invention of this application includes, for example, Japanese Patent Unexamined Publication No. H9-281138.
However, since the AGC circuit includes many analog elements, the temperature properties of the elements are accumulated and the size of the AGC circuit is increased. It is therefore difficult to make the amplitude of the sense element constant. As a result, the detection accuracy of the inertial force sensor is affected.